The Power of Rain: Science, Storms, and Silent Grace Behind a Drop of
Rain
It was raining exceedingly heavily for several hours in my place here
in Gombak, Selangor yesterday on 29 March 2026 . I remember a similar occurrence
way back during the second week of December 2021 These incidences prompted me
to write this article on
“The Measure of Rain: Physics, Power, and Providence”
The rains came without rest, day after day, night after night—falling
endlessly over Selangor. Sleep became a stranger to me, not only because of the
relentless sound of rain upon the roof, but also due to a lingering pain in my
leg from a venous stasis ulcer that had troubled me since the
time of the COVID pandemic.
And so, in those long sleepless nights, as the rain poured down in
sheets, a simple yet profound question arose in my mind:
Where did all this water come from? And how powerful was this rain, really?
Peninsular Malaysia is shaped by geography in a most interesting way.
Running like a spine from north to south is the great Titiwangsa Mountains,
with Gunung Tahan rising to over 2,000 metres above sea level. These mountains
form a natural barrier, often shielding the western coast from the full force
of the north-east monsoon, which typically drenches the eastern regions of the
peninsula.
Most rain-bearing clouds in the tropics form below about 2,500 metres, and under usual conditions, the mountain range prevents much of this moisture from crossing over. Yet yesterday (March 29, 2026) afternoon till evening, and also way back in December 2021, something unusual occurred. The rains broke through, and the western states, especially Selangor—experienced extraordinary downpours.
Rainfall is usually reported in millimetres, a unit that many accept
without fully appreciating its meaning. In reality, 1 millimetre of rain
represents 1 litre of water falling over every square metre of land. This
simple relationship allows us to translate rainfall into something far more
tangible: volume and mass.
During that extraordinary period, parts of Selangor recorded rainfall
exceeding 380 millimetres.
Now consider this:
Selangor spans an area of about 8,104 square kilometres. If we
imagine, for simplicity, that this rainfall was spread evenly across the entire
state, the total volume of water would amount to:
over 3 billion cubic metres of water
or more than 3 trillion litres
In terms of mass, this is approximately:
3 trillion kilograms of water falling from the sky
Such a figure is almost beyond comprehension. It is no wonder that rivers overflowed, drainage systems failed, and entire housing areas were submerged beneath floodwaters.
To better grasp this immense quantity, let us compare it with the
capacity of our water reservoirs. A typical dam in Selangor holds on the order
of tens to hundreds of millions of cubic metres of water. The rainfall from
this single event alone would have been sufficient to fill many of these
reservoirs dozens of times over, if it could all have been captured.
But of course, nature does not distribute water so conveniently. Rain falls unevenly, rivers channel it rapidly downstream, and when the volume exceeds the land’s capacity to absorb or carry it, floods become inevitable.
Yet an even deeper question arises:
What is the source of the energy behind such immense rainfall?
The answer lies far beyond our skies, in the Sun.
The Sun continuously bathes the Earth with energy, at a rate of about 1.366
kilowatts per square metre at the top of the atmosphere. This energy drives the
evaporation of vast quantities of water from the oceans, especially from warm
bodies such as the South China Sea. Invisible water vapour rises into the
atmosphere, carried by winds across great distances.
As this vapour cools and condenses into clouds, enormous amounts of
energy are released. This process is far more than the simple falling of
rain—powers the towering clouds, the storms, and the monsoon systems we
experience.
If we estimate only the gravitational energy involved in lifting this
mass of water to a height of a few kilometres, we obtain a figure on the order
of:
10¹⁶ joules
This is already an enormous amount of energy. Yet in truth, it
represents only a small fraction of the total energy involved in storm systems,
where the release of latent heat during condensation plays a far greater role.
When compared to the Sun’s total energy output—about 3.8 × 10²⁶ joules
per second—the energy involved in even such a massive rainfall event is but a
tiny fraction. And yet, that tiny fraction is sufficient to reshape landscapes,
flood cities, and profoundly affect human lives.
1. Dam Capacities in Selangor
Sungai Tua (Batu) Dam→ 36.6 million m³
- Sungai
Selangor Dam
→ ~235 million m³ - Langat
Dam
→ ~31–35 million m³
Rainfall conversion:
Volume
= Rainfall (m) x Catchment Areas= (m^2)
Or in simple terms:
1 mm rain = 1 litre per m² = 0.001 m³ per m²
What Really Fills a Dam?
A dam is NOT filled by rainfall over the whole state
It is filled by rain over its catchment area (river basin)
Catchment Areas (Approximate)
1. Batu Dam → 50 km²
2. Sungai Selangor Dam → ~600 km² (typical basin scale from design & reservoir size)
3. Langat Dam → ~200–300 km² (approx. river basin)
Calculation on Rainfall Needed to Fill Each Dam
A. Batu (Sungai Tua) Dam
Capacity = 36.6 million m³
- Catchment
= 50 km² = 50 × 10⁶ m²
About 730 mm rainfall needed
B. Sungai Selangor Dam
- Capacity
= 235 million m³
- Catchment ≈ 600 km² = 600 × 10⁶ m²
About 400 mm rainfall needed
- Capacity
≈ 31 million m³
- Catchment ≈ 250 km
About 120–150 mm rainfall needed
REAL Example — Heavy Continuous Rain
Let us now imagine:
Scenario:
- Heavy
monsoon rain
- 50
mm per day
- Lasts
5 days continuously
Total rainfall:
What Happens?
Batu Dam:
- Needs
~730 mm
- 250 mm gives:
Only 1/3 full
Sungai Selangor Dam:
- Needs ~400 mm
More than half full
Langat Dam:
- Needs ~130 mm
Overflow likely → flooding
Not all dams respond the same way to rain
- Small
catchment → needs more rainfall
- Large
catchment → fills quickly
- Moderate
catchment → most sensitive to
floods
7. Why Floods Occur Even Before Dams Fill
Because:
- Rain
falls faster than rivers can carry
- Soil
becomes saturated
- Water
flows directly into rivers So flooding happens before dams are full
We now see something very deep:
- A
single storm of 200–300 mm
Can fill major dams or cause overflow and disaster
This is exactly what happened in December 2021.
And so, we come to a humbling realization.
The rains that fell over Selangor in December 2021 resulting in the floods that
followed, the rivers that overflowed, the lives disrupted, were all part of a
vast and continuous cycle powered by the Sun. From the quiet evaporation of
seawater to the towering clouds of the monsoon, from invisible vapour to
torrents of rain, it is a cycle of immense scale and power.
Without the Sun, none of this would exist. No winds would blow, no
clouds would form, no rains would fall.
As I lay awake through those long nights, listening to the relentless
downpour, I realized that what seemed like a simple act of rain was, in truth,
a manifestation of forces far greater than we often imagine.
It was not merely rain.
It was the power of the Sun, the oceans, and the atmosphere, working
together in a grand and ceaseless dance over our planet.
Let me now give my spiritual reflection — beyond the physics of rain
After all the calculations have been done, after the volumes measured
and the energies estimated, there remains something that numbers alone cannot
fully contain.
For what is rain, truly?
We have seen that it begins with the Sun—its radiant energy lifting
oceans into the sky, forming clouds that travel across vast distances before
returning to the Earth. Science explains this beautifully, and truthfully. Yet,
even in its precision, it points toward something greater.
For behind this orderly process lies a harmony that invites
reflection.
The oceans do not overflow endlessly into the skies, nor do the clouds
empty themselves without rhythm or restraint. There is balance, namely; delicate,
dynamic, yet enduring. The same forces that bring destruction through floods
are also those that sustain life: filling rivers, nourishing crops,
replenishing reservoirs, and sustaining every living cell.
Rain, therefore, is not merely an event. It is part of a cycle of provision.
In moments of great storms, such as the floods that struck Selangor, one
may be overwhelmed by the sheer force of nature. Homes are submerged, lives
disrupted, and the power of water becomes almost frightening. Yet even within
such events, one may ask:
Is there only chaos, or is there also purpose beyond our immediate
understanding?
From a spiritual perspective, the natural world often reveals both power
and provision intertwined. The same rain that floods also cleanses, renews, and
restores. The same rivers that overflow in one season sustain life in another.
There is a passage in the Scriptures that comes to mind:
“He makes His sun rise on the evil and on the good, and sends rain on
the just and on the unjust.”
— (Matthew 5:45)
Rain falls without discrimination. It is given freely, not earned. It sustains all life—plant, animal, and human alike. In this sense, rain may be seen not only as a physical process, but also as a quiet expression of grace.
And yet, there is another dimension to consider.
You reflected, my dear brother, on the immense energy involved—the
trillions of kilograms of water, the vast forces at work, all ultimately
powered by the Sun. Science tells us how this happens, but it does not
fully answer why such a finely balanced system exists at all.
Why should the Earth be positioned at just the right distance from the
Sun?
Why should water possess such unique properties; evaporating, condensing,
expanding, and sustaining life?
Why should the atmosphere behave in ways that allow this continuous cycle to
persist?
These are questions where science reaches its boundary, and contemplation begins.
For some, the answer lies in natural laws alone.
For others, these laws themselves point toward a deeper order—a design, or at
least a profound coherence that is not easily dismissed as mere accident.
I once beautifully reflected on
the human body as an intelligent system and wondered whether such intelligence
could arise without a guiding source. In much the same way, the water cycle of
our planet, so vast, so precise, and so essential, can evoke a similar sense of
awe.
Not as proof, perhaps, but as invitation.
And so, the rain becomes more than water.
It becomes a reminder:
- Of
our smallness in the face of nature
- Of
our dependence on forces beyond our control
- And
perhaps, of a provision that is given, not earned
In the quiet moments after the storm, when the waters recede and the
skies begin to clear, one may look back and see not only destruction, but also
renewal, the earth softened, the reservoirs replenished, life continuing.
Thank you for reading, dear friends and readers of my blog
References for further reading:
Meteorology & Rainfall Malaysian Department of Irrigation and
Drainage (DID Malaysia)
1. Malaysian Meteorological
Department (MetMalaysia)
2. Journal of Physics:
Conference Series (2020) — Rainfall data in Malaysia
3. Hydrology & Water Cycle
- NASA
– Water Cycle Overview
- NOAA
– Precipitation and storms
Solar Energy & Physics
- NASA
Solar Radiation Data
- European
Space Agency – Solar constant and Earth energy balance
Optional Spiritual Reference
The Holy Bible (e.g., Matthew 5:45, Psalm 147:8)
